closed mesh

This is not really opengl-specific question, but ideally, you will want a bounding volume for your mesh. A sphere or aabb (axis-aligned bounding box) for example should do the job. It will be a much faster operation to test if a point is inside a sphere or bounding box than testing against your whole mesh.

First do AABB/sphere test as dopeflow told you. The is it's in bouding volume cast a ray from point to infinity in random direction and count the number of triangles it hits.

count = odd --> inside
count = even --> outside    

ps: Is this openGL question...

You should never let your fears become the boundaries of your dreams.

[edited by - _DarkWIng_ on October 11, 2003 1:00:06 PM]